Photosensitive compositions containing o-quinonediazide compounds as excellent positive-working photosensitive compositions, have been used in production of lithographic printing plates and photoresists. Although several proposals have been made for increasing the sensitivity of these quinonediazide-containing positive-working photosensitive compositions, none of them have proved satisfactory. By decreasing the content of the quinonediazide compound, the sensitivity of the composition is increased, but, at the same time, the latitude in development (the period during which optimum development is accomplished, and this is expressed in terms of the longest development time in which the number of clear stages on a gray scale for a given concentration of developing solution remains on a certain level) is narrowed. The apparent sensitivity of the quinonediazide compound is also increased by adding a binder resin having great solubility in an aqueous alkaline solution, but, again, this system has a narrow latitude in development.
Methods have been proposed for adding sensitizers to photosensitive compositions containing quinonediazide compounds to increase their sensitivity, but none have proved completely satisfactory, all methods being defective in one way or another. For instance, U.S. Pat. No. 3,661,582 describes a method for providing an increased sensitivity by adding certain heterocyclic compounds such as 2-azacyclononane-2-one, indole, quinazoline and tetrazole, but the resulting composition has an extremely small latitude in development.
Japanese Patent Publication No. 42449/71 teaches the use of various additives, say, triphenylmethane dyes, benzaldehydem-tolyhydrazone, hydrocarbon halides and azo dyes, to provide an increased photographic sensitivity, but none of these compounds are particularly effective in achieving the intended object.
The addition of o-benzoic acid sulfimide, hydantoin or its derivatives, and thiohydantoin or its derivatives to achieve the same object has also been proposed in Japanese Patent Application (OPI) No. 36203/75 (the symbol OPI as used herein means an unexamined published Japanese patent application). The addition of cyclic acid anhydrides is another means to attain the same purpose, as taught in Japanese Patent Application (OPI) No. 80022/77 and in Comparative Example 2 to be described hereinafter. In either case, the addition of the proposed compounds in the amount sufficient to achieve the intended increase in sensitivity only results in an extremely narrow latitude in development. Japanese Patent Application (OPI) No. 54503/77 discloses a photosensitive copying material containing polyhydroxybenzophenone, but this compound is added primarily for the purpose of improving the adhesion to a photographic support, and no great increase in the sensitivity of the copying material is attained. Also, increased sensivivity can be realized by adding a condensation product of hydroxybenzophenone and formaldehyde as described in Japanese Patent Application (OPI) No. 73045/80 and in Comparative Example 3 to be given hereinafter, but, in this case, like the compound disclosed in Japanese Patent Application (OPI) No. 54503/77, the condensation product must be added in a considerable amount to realize the desired increase in sensitivity, and this unavoidably reduces the latitude in development and the chemical resistance.